High density EEG and arterial spin labelling MRI perfusion in the diagnosis and follow-up of patients with Moyamoya vasculopathies

Introduction: Moyamoya vasculopathy is a rare condition characterized by “puff of smoke” angiographic appearance. The natural history includes recurrent transient ischemic attacks, ischemic stroke or intracerebral bleeding. Pharmacological treatment is not effective in preventing these clinical events and patients may benefit from surgical revascularization, but the timing of surgery is still controversial, especially at the early stages of the disease. Although angiography is still the gold standard for diagnosis and evaluation of patients with moyamoya, it has several limitations because of its invasivity and occurrence of complications. In recent years, several new non-contrast MRI techniques have been developed to study intracranial arteries and brain perfusion, but their use still needs to be validated for clinical daily management. Moyamoya patients usually present a characteristic pattern a few minutes after hyperventilation is called the “rebuild up phenomenon” and disappears after successful revascularization surgery, making EEG a simple and non-invasive tool that can be easily compared with perfusion data in order to evaluate the results of surgery and to follow up the patients. Material and methods: We enrolled all pediatric patients with new-onset Moyamoya between 1 to 18 years old candidates for revascularization surgery at Our Institute. For all patients, a presurgical assessment with PEDMIDAS score for headache, high-density EEG, brain MRI with perfusion technique and longitudinal clinical follow-up for 18 months length was performed. Results: Thirteen patients completed the presurgical EEG evaluation (9 patients > 3 years with 64 channels EEG and 4 patients < 3 years with 19 channels, 7 male and 6 female) and 11 completed the post-surgical assessment. All patients underwent to revascularization surgery both with direct (mostly used in severely affected older patients) or indirect revascularization techniques or a combination of different techniques. None of the patients presented further cerebral ischemic events after revascularization surgeries during the follow-up period (median 24 months, range 10- 48 months). PEDMIDAS scores showed a significant improvement in all cases with a decrease in frequency, severity, and in total score. EEG NREM sleep power spectral density analysis of 6 patients of our cohort with Moyamoya vasculopathy revealed significant differences before and after revascularization surgery. Five over 6 patients showed an increase in the sleep spindles sigma band and 3/6 showed a delta band increase. Conclusion: EEG sleep studies showed significant differences before and after revascularization surgery in a subgroup of our cohort with change in Power Spectral Density of sigma and delta band, making EEG a non-invasive promising tool for Moyamoya patients evaluation. PEDMIDAS is a standardized questionnaire that can be easily used at diagnosis, as an outcome measure of revascularization surgery efficacy and during follow-up in Moyamoya patients presenting with headache.